The International Panel on Climate Change released its Fifth Assessment Report (AR5) in 2014. The AR5 has an update of knowledge on the scientific, technical, and socio-economic aspects of climate change. In this assignment, I have chosen to analyze the following finding as found in the Summary for Policy Makers:
“It is very likely that human influence has contributed to the observed global-scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century (1.4)” (IPCC SPM 2014).
I chose this finding because I had a keen interest in understanding the impact of human influence on climate change, specifically, in the frequency and intensity of daily temperature extremes since the mid-20th century. I, therefore, had a particular persuasion that the trail of references provided in this section will make it easy for me to comprehend how human activities have contributed to the adverse effects of climate change that we’re currently experiencing. Following the citation, I traced the identical text in the Synthesis Report. Based on the statement of the finding, the following sources, which I found to be highly reliable, were provided {WGI SPM B.1, SPM D.3, Table SPM.1, FAQ 2.2, 2.6.1, 10.6} (IPCC SR,2014).
According to the report in Working Group 1 (WGI SPM B.1), there is a similarity in the statement finding. Moreover, the statement also includes the level of scientific understanding (LOSU) very likely. Very likely implies a 90-100% likelihood of an outcome. The key text from the report includes:
Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and changes in some climate extremes (Figure SPM.6 and Table SPM.1). This evidence for human influence has grown since AR4. Human influence has likely been the dominant cause of the observed warming since the mid-20th century (Karoly, 2014). {10.3–10.6, 10.9} (IPCC WG1, 2013).
The Working Group II report gives a clear explanation of the finding statement. It provides reasons why human influence is mostly to blame for the changes in the frequency and intensity of daily temperature extremes since the mid-20th century. Section 1.3.3 of (IPCC WGII, 2014) explains that
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. Human influence on the climate system is clear; it has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and changes in some climate extremes (SPM)”.
The peer-reviewed publication that has been incorporated in the communicated the following points;
Southwest Australia has become increasingly dry over the past century. Simulations with a high-resolution global climate model show that this trend is linked to greenhouse gas emissions and ozone depletion. The escalated greenhouse gas emission and ozone depletion have been attributed to human influence (Karoly, 2014).
In conclusion, the finding did not alter the meaning or the level of scientific understanding (LOSU) across the various levels of IPCC reports. Moreover, the LOSU of very likely, which implied a 90-100% likelihood of an outcome. The peer-reviewed publication also confirmed that it is very reasonable that human influence has contributed to the observed global-scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century.